With the rising popularity of portable electronic devices, the requirements of non-volatile memory are increasing accordingly. Resistive random-access memory (RRAM or ReRAM) is a potential non-volatile memory for the next generation. Due to the merits of low power consumption, a small area, and fast operating speeds, the RRAM can be utilized to replace existing flash memory.
The memory cell of the RRAM may comprise a transistor and a resistor (1T1R). Since the resistive nature of the transistor is inversely proportional to the size of the transistor, the transistor must be maintained at a proper size in order that it does not affect the cross voltage of the RRAM memory cell. However, such a limitation causes the overall area of the device to be large, making miniaturization difficult. Therefore, the 0T1R or 0T2R RRAM are proposed.
When no transistor is used, the overall device area of the 0T1R or 0T2R memory cell can be greatly reduced. However, current can leak out from selected memory to unselected memory cells due to the lack of blockage provided by the transistor.